12
Resistance management
from the atmosphere and pump it into
a silo is a machine developed by the oil
industry, which is widely available.
“At a rate of 30 cubic metres an hour,
it costs about $5 worth of diesel to purge
a silo of oxygen all the way down to 0.05
per cent total content,” he says. “Best of
all, insects never acquire resistance.”
Another challenge relates to
infrastructure: silos leaking.
“The standards for sealed silos are
too low for nitrogen storage of grain,”
Mr Clarke explains. “The accepted
level on the seals for a silo is the loss
of half an inch (12.7 millimetres) of
water pressure in three minutes.”
The oxygen in the silo needs to be
purged long enough to kill all insects.
Mr Clarke has identified a relationship
between eradication time (for all
stages in an insect’s life cycle) under
IT’S ALL IN
THE SEAL
By Gio Braidotti
REPLACING OXYGEN IN grain storage
silos with nitrogen has proven an effective
way to remove insects at all stages of
their life cycle, leaving stored grain – be it
wheat or canola – preserved, residue-free
and subject to no withholding periods.
Nitrogen is also the preferred storage
option, says Western Australia grower
Doug Clarke, who is the earliest adopter
of the technology in its on-farm form.
Mr Clarke made the switch five
years ago on his Lake Grace property,
and has made his silos available to
Murdoch University researchers led by
stored-grain expert Professor YongLin
Ren, with support from the GRDC.
Mr Clarke has hosted visitors over
the years, including overseas buyers, and
says he has learnt the extent to which
insecticide-free grain is preferred by buyers.
While he says the system is
performing well, he is committed
to continuous improvement.
However, one challenge is that there
is currently no price signal favouring
residue-free grain to compensate for
the investment and the extra work
associated with nitrogen-based storage.
In relation to the technology itself, Mr
Clarke has no issue with existing oxygen-
purging systems. He says the nitrogen
generator needed to purify nitrogen
PHOTO:NICOLEBAXTER
Doug Clarke, Lake Grace, WA, checks the oxygen content of his silos using a handheld meter.
RESEARCH
TESTED
By Rebecca Jennings
GRDC-FUNDED RESEARCH THOUGH
the Plant Biosecurity Cooperative
Research Centre (CRC) is being put to
the test by growers and bulk handlers
at five sites across Australia.
Plant Biosecurity CRC grains coordinator
Dr David Eagling says the impact sites are
a partnership with industry to work through
implementation issues. Each site has different
industry partnerships and a different focus:
¢ in central New South Wales, the impact
site at the GrainCorp facility in Temora
focuses on testing a new paint-based
product to control storage pests;
¢ in southern Australia, research at the
nitrogen and grain temperature.
The eradication time is as low as one
week at high temperatures, at 20oC it
blows out to three weeks, and below that
temperature he says it does not work.
It is these circumstances that have
created resistance to insecticides and an
interest in the latest sealing technology.
“What I am saying is that the better
the seal, the better control you have
under any fumigant. We need to be
looking to the latest sealing technology,
including polymers and 3D printers,”
he says. “The area that now needs
improving is the silo manufacturing.” □
GRDC Research Code NPB00013
More information: Doug Clarke,
dclarke4@bigpond.com; Professor YongLin
Ren, y.ren@murdoch.edu.au;
www.grdc.com.au/NPB00004
Viterra facility at Bowmans, South
Australia, includes insect monitoring
to complement Plant Biosecurity CRC
investments in grain insect ecology;
¢ in the west, the focus has been at
the CBH facilities at the grain port
of Kwinana, where the team has
been putting low-oxygen/nitrogen
technology through its paces;
¢ in the northern Western Australian grain
region, the impact site is a partnership
with the Mingenew–Irwin Group (MIG),
with various activities located directly
on grower’s farms (a particular focus
over the past 18 months has been the
deployment of aeration technology
developed jointly by the GRDC and
the Plant Biosecurity CRC); and
¢ in southern Queensland, the site has
been a partnership with GrainCorp
with an assessment of sulfuryl
fluoride across various locations.
“The Plant Biosecurity CRC is
conscious that research needs to be
implemented into existing grower and
bulk-handler processes and management
to be successful,” Dr Eagling says.
“We are working on the best way to
do this, as well as looking at the benefits
of bringing together multiple research
findings that can be integrated in a systems
approach, rather than each one in isolation.
“The industry impact sites assess how
a range of research outcomes fit together
in the day-to-day operations on-farm, at
ports and in bulk-handling facilities.”
He says the impact sites provide
researchers with a central point for
field testing and involve growers
and bulk-handlers in deciding what
research to test and how to go about
evaluating the research findings.